New Jersey has suffered unthinkable devastation from hurricane Sandy, governor Chris Christie said on Tuesday, after the superstorm smashed into the state's famous shoreline and swept inland, killing at least three, leaving 2.4 million people without power and effectively bringing the region to a standstill.

"This is beyond anything I ever thought I would see," Christie said at a news conference as the eastern seaboard of the US woke to widespread destruction from Sandy. The storm made landfall close to Atlantic City, causing extensive flooding at the state's gambling mecca, and has left much of its famous 127-mile shoreline underwater.

Residents living on New Jersey's barrier islands have been cut off from the mainland, and levees have broken in northern New Jersey leaving at least four towns with up to 6ft of water. Some 5,500 people are currently housed in five shelters across the state and a sixth is being opened. Christie said every line in the state's rail system had been damaged, including major hubs Hoboken and Secaucus. Kearny rail yard was surrounded by floodwaters.

The state's roads are similarly devastated. Christie said there are 173 incidents statewide involving highway closures, including 7ft-high "debris fields". He asked people to avoid travel unless absolutely necessary and said employees should ask staff to stay home.

"We have a lot of work to do. I have absolute confidence that we will be able to do and do it together. I have confidence in the fact that we will have complete support from the president of the United States and the federal authorities," said Christie.

The governor, recently seen as a potential vice presidential pick for Republican hopeful Mitt Romney and a likely presidential contender in 2016, was full of praise for Barack Obama. He said the president had been "outstanding" and praised Obama's swiftness in designating New Jersey a disaster zone, opening up federal funds for relief work.

"I have to say, the administration the president, himself and Fema [federal emergency management agency] administrator Craig Fugate have been outstanding with us so far," Christie told ABC's Good Morning America. "We have a great partnership with them."

Christie said Obama had called Monday night and offered to help in any way he could. New Jersey has now been declared a major disaster area, opening up government funding for recovery efforts.

"I want to thank the president personally for his personal attention to this," said Christie.

On Fox News Christie was asked whether he would be touring the disaster-stricken state with Romney. "I have no idea, nor am I the least bit concerned or interested," Christie said. "I've got a job to do here in New Jersey that's much bigger than presidential politics, and I could care less about any of that stuff."

"I have a job to do," he added. "I've got 2.4 million people out of power; I've got devastation on the shore; I've got floods in the northern part of my state. If you think right now I give a damn about presidential politics then you don't know me."

Christie said Sandy had affected twice the number of people who were hit by last year's tropical storm Irene. He said it had taken eight days for the state to get back on track after Irene. "This may take longer," he said. Christie said weather conditions were still so bad that the full extent of the damage would not be known for the next 24-48 hours.